USE OF LITHIUM SECONDARY ELECTROCHEMICAL CELLS CONTAINING A BLEND OF A LITHIUM NICKEL OXIDE AND A LITHIUM MANGANESE IRON PHOSPHATE FOR AUTOMOTIVE APPLICATIONS

Abstract

The use of a blend of a lithium nickel oxide and a lithium manganese iron phosphate as an active material composition in the cathode of a lithium secondary electrochemical cell for automotive applications, such as hybrid and electric vehicles. This blend allows decreasing the porosity of a lithium manganese iron phosphate-based cathode. It also allows improving the detectability of a gas release in the cell in case of an abnormal operation of the cell. It allows lowering the cell impedance at a low state of charge, typically less than 30%, and reducing the impedance increase of the cell during the cell lifespan.

Claims

1. A method for lowering the porosity of a lithium manganese iron phosphate-based cathode of a lithium secondary electrochemical cell, said method comprising using a lithium nickel oxide in the lithium manganese iron phosphate-based cathode.

2. The method according to claim 1, wherein the lithium manganese iron phosphate-based cathode contains a blend of active materials comprising-: from 90 to 50 wt. % of the lithium manganese iron phosphate, the lithium manganese iron phosphate having the formula-: Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2-; 1>1-y-z≥0.5-; 0<y≤0.5-; 0≤z≤0.2 and M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo from 10 to 50 wt. % of the lithium nickel oxide, the lithium nickel oxide being selected from-: Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 (NMC) where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof, and Li.sub.w(Ni.sub.xCo.sub.yAl.sub.zM.sub.t)O.sub.2 (NCA) where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

3. The method according to claim 1, wherein the lithium manganese iron phosphate-based cathode contains a blend of active materials consisting of 10 wt. % of the lithium nickel oxide and 90 wt. % of the lithium manganese iron phosphate and a cathode porosity is less than or equal to 35%.

4. The method according to claim 1, wherein the lithium manganese iron phosphate-based cathode contains a blend of active materials consisting of 50 wt. % of the lithium nickel oxide and 50 wt. % of the lithium manganese iron phosphate and a cathode porosity is less than or equal to 25%.

5. The method according to claim 1, wherein the lithium manganese iron phosphate-based cathode contains a blend of active materials consisting of: from 45 to 55 wt. % of the lithium nickel oxide-; from 55 to 45 wt. % of the lithium manganese iron phosphate-; the lithiated nickel oxide and the lithiated manganese iron phosphate being in the form of particles; a particle size distribution of the lithiated nickel oxide being characterized by a first median volume diameter of the particles Dv.sub.50.sup.1; a particle size distribution of the lithiated manganese iron phosphate being characterized by a second median volume diameter of the particles Dv.sub.50.sup.2; wherein Dv.sub.50.sup.2/Dv.sub.50.sup.1≤0.7 and Dv.sub.50.sup.2≥500 nm, leading to a porosity of less than 30%.

6. The method according to claim 5, wherein the lithium manganese iron phosphate-based cathode contains a blend of active materials consisting of: from 45 to 55 wt. % of a lithium nickel oxide of formula Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 (NMC) where 0.9≤w≤1.1-; 0.6≤x-; 0.1≤y-; 0.1≤z-; 0≤t; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof-; from 55 to 45 wt. % of a lithium manganese iron phosphate of formula Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2-; 0.6≤1-y-z<0.9-; 0<y≤0.5-; 0≤z≤0.2-; M being selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo.

7. A method for improving the detection of a gas flow that is released in a lithium secondary electrochemical cell when the cell is overcharged, the lithium secondary electrochemical cell having a lithium manganese iron phosphate-based cathode, said method comprising using a lithium nickel oxide in the lithium manganese iron phosphate-based cathode of the lithium secondary electrochemical cell the cell.

8. The method according to claim 7, wherein the gas flow activates a safety device.

9. The method according to claim 8, wherein the safety device is activated by an excess pressure or an excess temperature inside the cell.

10. The method according to claim 9, wherein the safety device is an electrically conducting connection part electrically connecting at least one anode or at least one cathode of the cell to a terminal of the same polarity, wherein an excess pressure in the cell causes interruption of the current flow in the connection part.

11. A method for lowering the impedance of a lithium secondary electrochemical cell at a state of charge of less or equal to 30%, the cell having a lithium nickel oxide-based cathode, said method comprising using lithium manganese iron phosphate in the lithium nickel oxide-based cathode of the lithium secondary electrochemical cell.

12. A method for reducing the impedance increase of a cell during cycling of the cell, the cell having a lithium nickel oxide-based cathode, the method comprising using lithium manganese iron phosphate in the lithium nickel oxide-based cathode of the lithium secondary electrochemical cell.

13. The method according to claim 7, wherein the cathode comprises a blend comprising: from 90 to 50 wt. %, preferably from 70 to 60 wt. % of a lithium manganese iron phosphate of formula Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2-; 1>1-y-z≥0.5-; 0<y≤0.5-; 0≤z≤0.2 and M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo-; from 10 to 50 wt. %, preferably from 30 to 40 wt. % of a lithium nickel oxide selected from-: Li.sub.w(Ni.sub.xCo.sub.yAl.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof and Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

14. The method according to claim 13, wherein the lithium nickel oxide is Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x≥0.6-; y≥0.1-; z≥0.1-; t≥0-; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

15. The method according to claim 11, wherein the cathode comprises a blend comprising: from 90 to 50 wt. %, preferably from 70 to 60 wt. % of a lithium manganese iron phosphate of formula Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2-; 1>1-y-z≥0.5-; 0<y≤0.5-; 0≤z≤0.2 and M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo-; from 10 to 50 wt. %, preferably from 30 to 40 wt. % of a lithium nickel oxide selected from-: Li.sub.w(Ni.sub.xCo.sub.yAl.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof and Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x>0-; y>0-; z>0-; t≥0-; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

16. The method according to claim 15, wherein the lithium nickel oxide is Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1-; x≥0.6-; y≥0.1-; z≥0.1-; t≥0-; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

17. The method according to claim 1, wherein the lithium secondary electrochemical cell is part of a battery providing electric energy to an electric vehicle or a hybrid electric vehicle.

18. The method according to claim 11, wherein the lithium secondary electrochemical cell is part of a battery providing electric energy to an electric vehicle or a hybrid electric vehicle.

19. The method according to claim 7, wherein the lithium secondary electrochemical cell is part of a battery providing electric energy to an electric vehicle or a hybrid electric vehicle.

20. The method according to claim 12, wherein the lithium secondary electrochemical cell is part of a battery providing electric energy to an electric vehicle or a hybrid electric vehicle.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

[0011] According to the invention the cathode of the lithium secondary electrochemical cell comprises a composition of active materials, said composition comprising a blend of at least one lithium nickel oxide and at least one lithium manganese iron phosphate. The lithium nickel oxide has a lamellar crystalline structure. The lithium manganese iron phosphate has the same crystalline structure as the olivine.

[0012] The lithium nickel oxide may be selected from: [0013] Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 (NMC) where 0.95≤w≤1.1; x>0; y>0; z>0; t≥0; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof, and [0014] Li.sub.w(Ni.sub.xCo.sub.yAl.sub.zM.sub.t)O.sub.2 (NCA) where 0.95≤w≤1.1; x>0; y>0; z>0; t≥0; M being selected from the group consisting of B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

[0015] In one embodiment, the lithium nickel oxide is Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 (NMC) where 0.95≤w≤1.1; x>0; y>0; z>0; t≥0; M being selected from the group consisting of Al, B, Mg and mixtures thereof. Preferably M is Al and t≤0.05. The majority transition element is preferably nickel, that is x≥0.5, even more preferably x≥0.6. A high amount of nickel in the lithium nickel oxide is preferable since it provides a high energy to the lithium nickel oxide.

[0016] The lithium nickel oxide may be Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 where 0.9≤w≤1.1; x≥0.6; y≥0.1; z≥0.1; t≥0; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

[0017] For example, the lithium nickel oxide may be selected from LiNi.sub.0.6Mn.sub.0.2Co.sub.0.2O.sub.2 and LiNi.sub.0.8Mn.sub.0.1Co.sub.0.1O.sub.2.

[0018] In another embodiment, the lithium nickel oxide is Li.sub.w(Ni.sub.xCo.sub.yAl.sub.zM.sub.t)O.sub.2 where 0.95≤w≤1.1; x>0; y>0; z>0; t≥0; M being selected from the group consisting of B, Mg and mixtures thereof. Preferably, 0.70≤x≤0.9; 0.05≤y≤0.25; z≤0.10; t=0 and x+y+z+t=1. More preferably 0.75≤x≤0.85; 0.10≤y≤0.20. The lithium nickel oxide may have formula LiNi.sub.0.8Co.sub.0.15Al.sub.0.05.

[0019] The lithium manganese iron phosphate has the following formula: Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2; 1>1-y-z≥0.5; 0<y≤0.5; 0≤z≤0.2 and M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo. In one embodiment, 0.9≥1-y-z≥0.7 or 0.9≥1-y-z≥0.75. In one embodiment, 0.15≥y≥0.25. Typical formulas of the lithium manganese iron phosphate are LiMn.sub.0.8Fe.sub.0.2PO.sub.4, LiMn.sub.0.7Fe.sub.0.3.PO.sub.4, LiMn.sub.2/3Fe.sub.1/3PO.sub.4 and LiMn.sub.0.5Fe.sub.0.5PO.sub.4. The lithium manganese iron phosphate may be coated by a layer of a conductive material, such as carbon.

[0020] The composition of cathode active materials may contain active materials other than the at least one lithium nickel oxide and the at least one lithium manganese iron phosphate. Preferably, the composition of cathode active materials does not contain any active materials other than the at least one lithium nickel oxide and the at least one lithium manganese iron phosphate.

[0021] The lithium manganese iron phosphate-based cathode contains a blend of active materials which may comprise or consist of: [0022] from 90 to 50 wt. % or from 80 to 60 wt. % or from 70 to 60 wt. % of the lithium manganese iron phosphate with respect to the sum of the masses of all the active materials, [0023] from 10 to 50 wt. % or from 20 to 40 wt. % or from 30 to 40 wt. % of the lithium nickel oxide with respect to the sum of the masses of all the active materials.

[0024] The lithium manganese iron phosphate and the lithium nickel oxide may have the formulas described above.

[0025] The blend may consist of: [0026] about 90 wt. % of the lithium manganese iron phosphate with respect to the sum of the masses of all the active materials, [0027] about 10 wt. % of the lithium nickel oxide with respect to the sum of the masses of all the active materials. Such a blend exhibits a porosity of less than or equal to 35% and a capacity per surface unit of layer deposited on the current collector of 42 mg/cm.sup.2 (3 mAh/cm.sup.2) for prismatic cells and 46.4 mg/cm.sup.2 (3.3 mAh/cm.sup.2) for pouch cells.

[0028] The blend may also consist of: [0029] about 70 wt. % of the lithium manganese iron phosphate with respect to the sum of the masses of the active materials, [0030] about 30 wt. % of the lithium nickel oxide with respect to the sum of the masses of the active materials.

[0031] The blend may also consist of: [0032] about 50 wt. % of the lithium manganese iron phosphate with respect to the sum of the masses of the active materials, [0033] about 50 wt. % of the lithium nickel oxide with respect to the sum of the masses of the active materials. Such a blend exhibits a porosity of less than or equal to 25% and a capacity per surface unit of layer deposited on the current collector of 42.6 mg/cm.sup.2 (3.36 mAh/cm.sup.2).

[0034] According to the invention, the lithium nickel oxide and the lithium manganese iron phosphate used are each in the form of a powder. The size distribution of the lithium nickel oxide particles is characterized by a first median volume diameter Dv.sub.50.sup.1. The size distribution of the lithium manganese iron phosphate particles is characterized by a second median volume diameter Dv.sub.50.sup.2. The term “equivalent diameter” of a particle designates the diameter of a sphere having the same volume as this particle. The term “median” means that 50% of the volume of the lithium nickel oxide (or lithium manganese iron phosphate) particles consists of particles having an equivalent diameter of less than the Dv.sub.50 value and 50% of the volume of the lithium nickel oxide (or lithium manganese iron phosphate) particles consists of particles having an equivalent diameter greater than the Dv.sub.50 value. The particle size measurement can be carried out using a laser particle size measuring technique.

[0035] In a preferred embodiment, the porosity of the blend is less than 30% or less than or equal to 28% or less than or equal to 26% or less than or equal to 25%. This particularly low porosity can be achieved by using a blend consisting of from 45 to 55 wt. % of the lithium nickel oxide and from 55 to 45 wt. % of the lithium manganese iron phosphate and by selecting a Dv.sub.50.sup.2/Dv.sub.50.sup.1 ratio of less than or equal to 0.70 and a Dv.sub.50.sup.2 value of at least 500 nm or even at least 1.5 μm. In a preferred embodiment, the Dv.sub.50.sup.2/Dv.sub.50.sup.1 ratio ranges from 0.15 to 0.60. In an even more prefered embodiment, the Dv.sub.50.sup.2/Dv.sub.50.sup.1 ratio ranges from 0.30 to 0.50 or ranges from 0.30 to 0.40. A Dv.sub.50.sup.2/Dv.sub.50.sup.1 ratio ranging from 0.14 to 0.53 may be obtained by using lithium manganese iron phosphate particles having a Dv.sub.50.sup.2 ranging from 1.7 μm to 3.2 μm and lithium nickel oxide particles having a Dv.sub.50.sup.1 ranging from 6.0 μm to 12.0 μm. Preferably, the lithium nickel oxide is of the NMC type.

[0036] Examples of preferred compositions leading to a blend exhibiting a porosity of less than 30% are as follows: [0037] from 45 to 55 wt. % of a lithium nickel oxide selected from: [0038] Li.sub.w(Ni.sub.xMn.sub.yCo.sub.zM.sub.t)O.sub.2 (NMC) where 0.9≤w≤1.1; 0.6≤x; 0.1≤y; 0.1≤z; 0≤t; M being selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof; [0039] from 55 to 45 wt. % of a lithium manganese iron phosphate having the following formula: Li.sub.xMn.sub.1-y-zFe.sub.yM.sub.zPO.sub.4 where 0.8≤x≤1.2; 0.6≤1-y-z<0.9; 0<y≤0.5; 0≤z≤0.2 and M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo. Preferably, 0.7≤1-y-z≤0.9 or 0.75≤1-y-z≤0.9.

[0040] The electrode porosity is defined as the percentage of the volume of the pores to the geometric volume of the electrode. The volume of the pores encompasses the volume of the void present between the particles of the compounds in the layer deposited on the electrode current collector and the volume of the pores inside the particles of the compounds in the layer deposited on the electrode current collector. The pores inside the particles encompass the accessible pores and the inaccessible pores. The electrode porosity may be obtained through the two following methods: [0041] In a first method, the mercury technique is used to determine the volume of the pores. The geometric volume of the electrode is obtained by multiplying the thickness of the layer deposited on the current collector by the area coated by the layer. The porosity is obtained by calculating the ratio between the volume of the pores and the geometric volume of the electrode. [0042] In a second method, the theoretical density d.sub.true is calculated starting from the density of each compound in the layer deposited in the current collector. The bulk density d.sub.bulk is calculated knowing the mass and the volume of the layer deposited on the current collector. The relationship which links the porosity with the true density and with the bulk density is the following:

Porosity=1−(d.sub.bulk/d.sub.true)

[0043] Porosity of a cathode containing lithium manganese iron phosphate as the sole active material is generally at least 40%. The addition of only 10% by weight of lithium nickel oxide to lithium manganese iron phosphate is sufficient to reduce the cathode porosity down to about 35%. The addition of 50% by weight of lithium nickel oxide reduces the porosity down to about 25%. The cathode porosity of the blend generally ranges from 25 to 35%. Thanks to the porosity reduction, the invention allows preparing a cathode containing a higher amount of lithium manganese iron phosphate per surface unit. The blend of LMFP with NMC or NCA overcomes the problem of low density by enabling low porosity electrodes to be achieved and thus makes high energy LMFP system possible.

[0044] The blend of the at least one lithium nickel oxide and the at least one lithium manganese iron phosphate also allows a more gradual release of gas in the cell container should the cell be subjected to an overcharge. Consequently, the pressure inside the cell increases gradually. The heat release occurs at a lower rate than when the lithium manganese iron phosphate is used as a sole active material. The gradual pressure increase allows the activation of a safety device before the temperature reaches a threshold value beyond which the risk of thermal runaway is significant. This result is unexpected since it is known in the art that phosphates of the olivine family are more stable thermally than lithium nickel oxides. Although it may be recognized that a LMFP-based cathode exhibits a better thermal stability than a nickel oxide-based cathode and releases less heat when it is exposed to an excessive external heat (overheat), this does not hold true when the LMFP-based cathode is exposed to an overcharge. During an overcharge of an LMFP-based cathode, the current keeps flowing through the cell, which is not the case when the cell is only exposed to an excessive external heat. The overcharge current is almost entirely used to oxidize the electrolyte. This oxidation reaction causes a sudden gas evolution which the present invention aims at moderating. The Applicant found that although lithium nickel oxides generate a higher amount of energy when overcharged the amount of energy is released in a more gradual manner thereby improving the detectability of an overcharge condition. Gas is released at a rate allowing the activation of safety device before the onset of a thermal runaway. Typically, when the cathode contains a blend of a lithium nickel oxide and a lithium manganese iron phosphate the safety device activates at less than 130-140° C. whereas when the cathode contains only lithium manganese iron phosphate the safety device activates at a temperature of at least 130° C. The gas evolution signal provided by the blend allows an earlier detection that the cell state of charge approaches 100%. The gas evolution signal provided by nickel oxide cathodes provides additional warning and mitigation tool for managing abuse of the system.

[0045] Another benefit of the invention is that the addition of LMFP offsets the impedance increase of nickel oxide cathodes at low state of charge maximizing the use of NMC or NCA cathode material at any rate or temperature. This way using the blended LMFP/NMC (or NCA) cathode energy densities within 3% to 5% of nickel oxide only cathodes can be achieved. The blend according to the invention may be used in the cathode of a lithium secondary electrochemical cell intended to power a hybrid or electric vehicle. The increase in energy density provides an extended range to the electric vehicle.

[0046] Additionally the voltages of both LMFP and nickel oxide cathodes are well matched creating a SOC curve with slopes and plateaus. LMFP exhibits two voltage plateaus at 3.5 V/Li° and 4.05 V/Li° while NMC gives a slope from 3.5 V to the end-of-charge voltage. Such SOC curve enables easy SOC management. The excess Li in a nickel based cathode allows for gradual voltage increase during overcharge and enables detection and prevention by electronics. The benefit is an easier end-of-charge detections and an easier management of the battery by the battery management system.

[0047] The lithium manganese iron phosphate and the lithium nickel oxide may be blended through any method known in the art, such as ball mill.

[0048] The cathode is prepared in a conventional manner. It consists of a conductive support used as a current collector which is coated with a layer containing the active material composition and further comprising a binder and a conductive material. The blend of active materials is generally mixed with one or more binders, the function of which is to bind the active material particles together and to bind them to the current collector on which they are deposited. The current collector is preferably a two-dimensional conductive support such as a solid or perforated strip, generally made of aluminium or of an aluminium alloy. The binders which can typically be used are selected from the group consisting of polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyamideimide (PAI), polyimide (PI), styrene-butadiene rubber (SBR), hydrogenated nitril-butadiene rubber (HNBR), polyvinyl alcohol, polyacrylic acid, and a mixture thereof. The conductive material is generally carbon. A solvent is added to the resulting blend. A paste is obtained that is deposited on one or both sides of the current collector. The paste-coated current collector is laminated to adjust its thickness.

[0049] The composition of the paste deposited on the current collector may be as follows: [0050] from 75 to 96% of the active material composition, preferably from 80 to 90%. [0051] from 2 to 15% binder(s), preferably 4%; [0052] from 2 to 10% carbon, preferably 4%.

[0053] Cells are produced in conventional manner. The cathode, a separator and the anode are superposed. The assembly is rolled up (respectively stacked) to form the electrochemical jelly roll (respectively the electrochemical stack). A connection part is bonded to the edge of the cathode and connected to the current output terminal. The anode can be electrically connected to the can of the cell. Conversely, the cathode could be connected to the can and the anode to an output terminal. After being inserted into the can, the electrochemical stack is impregnated with an organic electrolyte. Thereafter the cell is closed in a leaktight manner. The can also be provided in conventional manner with a safety valve causing the cell to open in the event of the internal gas pressure exceeding a predetermined value. The shape of the can is not limited, it can be a cylindric shape or a prismatic shape in the case of plane electrodes.

[0054] Several electrochemical cells may be connected in series or in parallel or in parallel-series or in series-parallel to form a module. The cells are combined within one container forming the envelope of the module, each cell being equipped with devices necessary for the electrical connection to the other cells of the module, for example in the form of metal strips (busbars), devices for measuring the operating parameters of the cell (temperature, voltage, current) and optionally safety devices (valve, membrane seal). The modules are connected together to form the battery which may be used to power a pure electric vehicle or an hydrid vehicle or a plug-in hybrid vehicle.